Rotating drum typewriting machine



Nov. 5, 1957 s. B. TlBBLlNG 2,312,048

ROTATING DRUM TYPEWRITING MACHINE Filed Jan. 4, 1954 5 Sheets-Sheet 1 vINVENTOR;

-BY 5H9 Bffibbhng hgwwfw Nov. 5, 1957 s. B. TIBBLING ROTATING DRUMTYPEWRITING MACHINE 5 Sheets-Sheet 2 'Filed Jan. 4, 1954 N wc INVENTOR.

BY 5117 B. Tcbblinj Nov. 5, 1957 s. B. TlBBLlNG 2,81

ROTATING DRUM TYPEWRITING MACHINE Filed Jan. 4, 1954 5 Sheets-Sheet 3 asf 56 INVENTOR.

BY 511351 112511 n Nov. 5; 1957 s. B. TIBBLING ROTATING DRUM TYPEWRITINGMACHINE 5 Sheets-Sheet 5 Filed Jan. 4, 1954 N] a fa L 7 .T. s W :0 mm m:

United States Patent ROTATING DRUM TYPEWRITING MACHINE Stig B. Tibbling,Hyde Park, N. Y., assignor to International Business MachinesCorporation, New York, N. Y., a corporation of New York ApplicationJanuary 4, 1954, Serial N 0. 402,015

18 Claims. (Cl. 19717) This invention has to do with a powered operatingmeans or action for such instrumentalities as the type bars of aprinting mechanism such as a typewriter. While not so limited inusefulness, it is described here as it is applied to a typewritingmachine of conventional design in other respects (not described indetail), such as keyboard, carriage, roller platen, ribbon, andmechanism for moving the carriage, the roller platen and the ribbon.

Objects of this invention are to provide a typewriting machine which issimple and positive in operation, which uses a minimum of mechanicalelements, which causes the impression to be made by the free flightmovement of the type bars, which permits independent adjustment of theimppression of the respective type bars, which has a control for varyingthe impression of the type bars as a group, and which advances the artgenerally.

The novel means for working the type bars includes a constantly runningpower-driven impeller unit serving all of the type bars alike; 2. seriesof mechanical actuators for the several type bars; and selector meanswhich may be either key-operated or remotely controlled for subjectingthe desired one of these actuators to the action of the common impellerunit whereby it moves the type bar against the platen for a printingimpression.

The general organization of the type bar operating mechanism or actioncan be understood from the nature of the preferred impeller unit shownand from its action in relation to the type bar actuators and theirselectors considered generally. The power-driven impeller unit is inconstant rotating motion during any period of operation of the machineand carries a series of cams, any one of which is capable of imparting alongitudinal thrust to a type bar actuating link when one end of thelink is moved into the path of these cams. The impeller unit shown,which is in the form of a rotating disc having an annular flange formingan open drum with a series of cams spaced around the inner surface ofthe flange, is located at the back of the machine and rotates about atilted axis. A bank of type bar actuating units, each controlled by aparticular selector such as a key, is so mounted at a midportion of theframe as to engage respectively an arcuate series of links which projectrearwardly into the space bounded by, the flanged disc of the impellerunit with the extending ends of the links normally clearing the cams.The keys are at the front ends of a bank of forwardly extending pivotedarms which are interconnected with the corresponding links. Upondepressing any one of the keys, the corresponding type bar actuatinglink is dropped into the path of the cams so that the first random camwhich passes the point where the end of the link is located comes intoengagement with the link end to exert a longitudinal forward thrust uponthe link. The resulting forward motion of the'link swings the pivotallyattached type bar upwardly against the platen. Provision such as aspring is made for restoring the parts to their idle positions whereinthe actuating link is restored to a position. clear of the cams and thetype bar is returned to its rest position as soon as ICC 2 the key isreleased. Provision is also made forvarying the spring force andtherefore the adjustment of the impression. I

In addition to the novel combination involved in the generalarrangement, particular novelty resides in the construction of the typebar actuating means by which the impelling thrust causes the type bar toswing against the platen and by which the subsequent restoration to idleposition is effected, and in the means by which the actuating link ofthe desired type bar is moved into the path of the cams when aparticular key is struck.

It is immaterial which impeller cam engages the actu ator link subjectedto the impeller drum action, since all of the cams act alike. The speedof rotation of the impeller drum and the spacing of its cams are suchthat the cams pass a given point in rapid succession, and there is noappreciable time lag between the movement of the.

end of an actuating link into the cam path and the temporary engagementof it by a random cam. The interval in which a cam is in positiveengagement with an actuating link is brief and occurs over less than thefull travel of the link, so that during the final phase of the motion ofthe link and its type bar the link and the bar are in free flight.

These and other objects and aspects of the invention will be apparentfrom the following description of two specific embodiments of theinvention which refer to drawings wherein:

Fig. 1 is a schematic isometric view of the operating elements for oneof the type bars;

Fig. 1a is a fragmentary view of the drum cams;

Fig. 2 is a side elevation view in partial section of the operatingelements in their normal positions;

Figs. 3 and 4 are views similar to Fig. 2 in sequential operatingpositions;

Fig. 5 is a diagrammatic view of an electromagnetic unit;

Fig. 6 is a plan view of the electromagnetic actuators; and

Fig. 7 is a sectional view on line 7-7 of Fig. 6.

The mechanism will now be described in detail, first in a form in whichthe key controlled operation of the particular type bar actuator tosubject it to the action of the impeller drum is entirely mechanical,and then in an alternative form in which the mechanism includeselectromagnetic components.

The mechanical form is illustrated by a single type bar unit or action,a number of similar units being used in accordance with the number oftype bars in the machine. This unit mechanism, as to main parts,consists of a pivoted type bar 10 (Fig. 1) having a downwardly andrearwardly extending bell crank portion 11 7 beyond its pivot 12 in thearcuate frame 15 which serves to mount the bank of type bars; alongitudinal rearwardly extending type bar actuating link 20 pivotallyconnected as at 21 to the bell crank portion 11 and extending at itsother end into proximity to the earns 35 on the impeller drum 30; amanually operated key 40 on a pivoted arm 41 extending to the front ofthe machine; and a cable 45 and associated parts through which downwardmotion of the key 40 is caused to lower the extremity of the actuatinglink 20 into the path of the earns 35 whereby the thrust of a random oneof the cams upon the end of the actuator link 20 moves the latterforward and swings the pivoted type bar 10 up against the platenroll 50(Fig. 2).

lateral play in one. of the slots formed by an arcuate series frame 15secured to the frame of the machine in front of the impeller drum 30.The type bar is'pivotally mounted to rotate freely about a heavy wire12,1"unning through andtightly fitting in a series of aligned holes'inthe fins 16. As in known machines, the heads 14 of the several type bars10 are bent laterally with respect to the bars in such different amountsthat the heads of all of them strike the platen in the same verticalzone of action, past which the platen is moved in the usual way.

The impeller drum 30 consists of a disc 31 mounted on a forwardlyextending spindle 32 which is journalled in bearings (not shown)vcarried in the frame, the axis of the spindle being inclined upwardly bya small amount at its forward end as shown. The spindle .32 is drivenina counter-clockwise direction (as seen in Fig. l) at a constant speedby an electric motor (not shown), and has a conventional pawl andratchet (not shown) to prevent reverse rotation. Extending forwardly atthe outer 1 rim of the disc 31 is an annular flange 36 on the innersurface of which are raised the series of spaced impelling cams 35. Eachcam (Fig. 1a) is of thin cross-sectional area and extends across theflange 36 at an angle to the axis of the impeller drum so that, inreference to the direction of travel, the cam has a concave forward face37 which forms the operative cam surface. The momentum of the type bar10 and link 20 will at some point of the travel cause disengagementbetween cam 35 and the link, after which the type bar will be in freeflight.

Within the flange 36, and spaced slightly from the top surface of thecam 35 on the flange, is a fixed arcuate comb 38 which serves as aspacer and guide for the rearward ends of the type bar actuating links20. Each link 20 lies between adjoining teeth 39 of the comb with a freefit giving lateral support but permitting both an edgewise pivotalmotion into the path of the cams 35 and also the endwise longitudinalmotion involved in the operation of the type bar 10. The teeth '39 ofthis arcuate comb are in alignment with the fins 16 of the arcuate framefor the type bars 10.

A helical tension spring 22 connects a bell crank portion 23 extendingdownwardly from the forward end of the type bar actuating link to afixed plate 24 (Fig. 2) on the main frame of the machine so that thespring serves to bias the rear end of the actuating link upwardlyagainst the body portion of the comb 38, and serves also to retract thetype bar to its normal position shown=in Fig. 2. Since in movingupwardly-to printing position the type bar moves against the tension ofthis spring,-the biasing force affects the impression.

To permit adjustment of the biasing force on the type bar 10, a rod 25which at one end is connected to the end of the bell crank portion 11 ofthe type bar 10 extends rearwardly through the fixed frame plates 26 andanother movably mounted abutment plate 27. At its rearmost end this rodis threaded to engage a circular nut 28 which is slotted to receive ascrewdriver. The end of the nut 28 bears against a'helical compressionspring 29 surrounding the rod 25 and lying between the nut end and theabutment plate 27 Turning the circular nut 28 gives adjustment of theforce exerted by the spring 29 so as to vary the impression upon theplaten roll 50 i by the individual type bar, whileforward or backwardmovement of the abutmentplate 27 provides a common adjustment of theforce of allof the springs 29 in the several type bars 10.

The key operated means for bringing the type bar actuating link 20 intothe path of the drum earns is. next described. The key is attached nearthe forward end of a horizontal arm 41 pivotally mounted on a heavy wire42 serving to mount all of the like key arms. A tension spring 43,connecting a downwardly directed leg at the forward end of the key arm41 to a fixed portion of the main frame as at 44, holds the key normallyin raised position. A cable 45, which transmits motion of the key 40 tothe lever 51 acting on the actuating link 20, is attached at its forwardend to a ratchet wheel 46 carried on a transverse shaft 47 serving alsoto mount like wheels for other like units. By the selection of theparticular tooth 49 of the ratchet wheel 46 engaged by a spring pawl 48extending down from the key arm 41 adjustment can be made in the tensionof the cable 45. The ratchet wheel 46 also serves as a bell crank in asmuch as it changes the vertical motion of the pawl 48 into a horizontalmotion which draws the cable forward when the key 40 is struck.

The cable extends through an enclosing housing to connect with a bentlever 51 which is pivoted at 52 on an extension 38a from the comb 38.This bent lever 51 has a lateral lug portion 55 which is bent over anddown so that it overlies a finger 56 which projects outwardly from theside of the type bar actuating link 20, so that when the cable 45 isdrawnforward by action of the ratchet wheel 46, upon depression of thekey 40, the bent lever 51 isrotated about its pivot 52 to move theactuating link 20 down against the force exerted by the spring 22 and aball detent spring 60 which normally hold the end of the link clear ofthe impelling cams 35. This depression of the actuating link 20 brings aball which is biased by the spring 60 into engagement with the bevelednose upon the end of the link so that the force exerted by the springmoves the link downwardly to bring its cam follower toe portion 57 intothe path of the earns 35 as shown in Fig. 3.

The camming action of the forward face 37 of the cam 35 upon camfollower portion 57 thrusts the actuating link 20 forward'in alongitudinal direction (i. e., to the right) thus swinging the type bar10 counterclockwise about its pivot 12, against the force of the springs22 and 29. The length of the cam surface 37 is such that the link 20andtype bars 10 are positively impelled through only a part of theirtravel, for instance through of swing of the type bar in one desirableform; and for the rest of their travel the arm and type bar are in freeflight until the type bar 10 strikes the platen roll 50.

A comparison of Figs. 2, 3 and 4 shows the different positions of thepartsin a cycle of action. In Fig. 2, the type bar 10 is in its idleposition with the type head 14 on the rest and the cam follower end 57of the actuating link 20 in raised position clear of the impelling cams35 so that the ball spring detent 58 is below the beveled nose 59 of thelink. Both the biasing springs 22 and 29 andthe spring detent 58 thusserve to hold the end of the link 20 clear of the cams 35. Fig. 3 showsthe actuating link 20 moved into operative position, as a result ofrocking of the bent lever 51 so that the cam follower 57 is in the campath and its nose 59 engaged by the detent ball 58, which is thecondition set up when the key 40 is struck to bring the cable 45 intooperation. In Fig. 3 the effective cammed surface 37 of one of the cams35 is shown first coming into engagement with the cam'follower portion57 of the actuating link 20. The cam 35 has not yet thrust the link 20forward, so the type bar 10 is still at rest under the influence of thespring 22. Fig. 4 shows the condition an instant later as the cam hasadvanced and has thrust the actuating link 20 forward (to the right) sothat the link is free of the cam surface, with the result of swingingthe type bar 10 up against the platen roll 50. Because of thelongitudinal sliding movement which can take place between the linkfinger 56 and the lug 55 of the bent lever 51, this action takes placeirrespective of whether or not the key 40 has been released. As soon asthe key 40 is released, the key spring 43 lifts the key bar 41 with itsspring pawl 48 so that the ratchet wheel 46 is free to be turned in aclockwise direction as the bent lever 51 and the link 20 are returned tothe position in Fig. 2 by the action of the springs 22 and 29 upon allrestraining forces being released.

The alternative form which is the subject of Figs. 5 and 6 retains theimpeller drum 30 with its cams 35, the type bars 10 and the actuatinglinks 20, and the biasing spring 22 which operates as before. Theditference is in the mechanism for moving the desired type bar actuatingarm link into the cam path. For the key-controlled means of Figs. 1-4,comprising the ratchet wheel 46, cable 45 and depressing bent lever 51individual to each particular actuating link 20, this alternative formsubstitutes an electromagnetic motive means for effecting the same endresult which may be key operated or remotely controlled by a combinationof electric pulses obtained for example in a remote control circuit ofan electric typewriter.

, The motive means proper are fixedly mounted within the drum-shapedspace bounded by the flange 36 of the impeller drum 30. Consideringfirst the main parts and general arrangement this mechanism has anarcuate (semicircular) series of thin radial fingers 96 each of which isassociated with a particular pair of type bar. actuating links 20. Thelinks as before are in an arcuate bank and extend rearwardly into theslots between the teeth 39 provided by the comb member 38. The fingers96 are in a generally vertical plane in front of the motive unit and atright angles to the longitudinal actuating links and those in thecenterof the arc extend downwardly, as shown in thelower part of Figs. 6 and7. In its normal position, each finger is withdrawn radially inwardlyfrom its associated pair of links 20 and is in register with the spacebetween them immediately in front of the corresponding comb tooth 39 sothat if the finger is moved axially (radially outward) it would enterthat space, clearing the links on either side. i

The manner of bringing a particular finger 96 into play to move one ofits associated actuating links 20 into the cam path is to displace thefinger sidewise until it is in register with the top edge of the link,and then to advance the finger axially so that the end thereof engagesthe link to move it into the position wherein the ball 58 and the spring60 move the cam follower portion 57 into the cam path, all with the sameresult as described above where the link is so moved by the bent lever51 operated by cable from the key 40. One way of so displacing a finger96 is to mount it pivotally and to have a means adjacent the finger,movable laterally upon depression of the proper key, to deflect the freeend of the finger.

Apart from the fingers 96, the mechanism consists of ('1') anelectromagnetic controlled motive means for selectively deflecting ordisplacing the finger 96 which operates the particular type bar 10 to bestruck against the platen roll 50, together with (2) a furtherelectromagnetic controlled motive means for advancing the deflectedfinger axially and thereby move the type bar actuating link 20 into thepath of the cams 35. These means can be individual to each actuatinglink 20, as in the fully mechanical form already described, but I preferin order to minimize the number of components a mechanism such as theone illustrated in Figs. 6 and 7 in which a motive means of each sortserves several links and associated type bars. This is made possible bythe use of the displaceable fingers 96 as the agency for moving thelinks 20 and by a proper relation of the respective electromagneticmotive means to diiferent fingers.

A first fact of which advantage is taken is that a single motive meansmay serve to advance axially a group of several fingers 96simultaneously, but with the result of moving only one actuating link 20into the cam path, if only one finger of the group so advanced has beendisplaced laterally into operative register with an actuating arm. Allof the other fingers of the group of fingers 96 so advanced and notbeing displaced laterally will pass between their associated arms 20.Further, when the fingers 96 are thus divided into groups with a motiveunit for-independently advancing each group, a single displacthem are inthe same group for purposes "of advancement. The reason is that ifseveral fingers 96 from different groups are simultaneouslydisplaced,'including the finger that is associated with the particularlink 20 to be moved into the cam path, so that if the only groupadvanced is the group containing that particular finger, then thedisplacement of a finger in each of several other groups not advancedbecomes immaterial. In this way it is possible to reduce materially thenumber of motive units needed for the lateral displacing step and forthe axially advancing step of the various fingers 96. I prefer to reducethe number of fingers required by having each finger 96 serve twoactuating links 20 and by providing for the lateral displacement of eachfinger in either directionso that the finger can be brought intoregister with either the actuating link lying to its right or to thelink at its left.

Fig. 5 illustrates the general scheme diagrammatically, withoutreference to the character of the motive means or of the control forthose means. It shows only sixteen actuating links 20, out of a totalbank of fifty-six, and eight operating fingers 96 each of which isnormally in register with the space between two adjoining links, therethus being one finger for each two adjacent links. The fingers 96 aredisplaceable by being deflected either to the right or to the left sothat each may be put in register with either of its two associated links20 to move the link into the cam path when the fingers are advancedaxially, i. e., radially outward. The eight fingers are in two groups offour each, with separate motive means a and 90b for advancing each groupof four respectively; so that from the standpoint of association withthe finger advancing means, the links may be considered as being in twogroups of eight each. To identify the corresponding links of each group,the sixteen links are designated A, a, B, b, etc., the same letter beingused in upper and lower case to designate the two links served by asingle finger. A single motive means 114 is used for displacing the twofingers associated with the Aa fingers of each group, and isdouble-acting so that when operated in one direction it deflects thosefingers to the left to register with the A links, and when operated inthe opposite direction it deflects those fingers to register with the alinks. There are three other similar motive means (not shown), one forthe finger serving the B--b links, another for the Cc links, etc.

if now, for example, the letter M is the character 13 on the type bar 10actuated by the A arm of the first group, for which the fingers 96 areserved by the advancing motive means 90a, the arrangement is such thatwhen the M key is struck, the displacing motive means 114 is energizedto displace the finger that serves that A-a links of each group to theleft to bring the left hand finger of each group into register with theA link associated with each group. Striking such key also causesenergization of the particular advancing means 90a serving the left handgroup which includes the finger for the type bar carrying the letter M.In the case shown, that is the A link of the left group, served by theadvancing means 90a. The resulting advance of the left hand group offingers 96 therefore moves that particular link into the cam path. Theother fingers of that group, being undeflected, advance into the spacesbetween lines; While at the second right hand group, although its lefthand finger is also deflected, nothing happens because that group offingers is not advanced by the motive means 90b.

It will be evident that this reduces the number of fingers 96, ofadvancing means 90, and of displacing means 114; that as many groups maybe formed as are needed for the total number of type bars 10 to beserved; and that the basic idea is to provide as many displacing unitsas there are fingers in each group served by a single advancing means,the displacing unit being double-acting when a finger is displaceable intwo directions to serve two links. If there is a finger for each link,with a dis placing unit serving todeflect it inthe single directionthenrequired, there still are as many displacing units as there-arefingers in each group served by a single advancing unit. 7

It will be evident also that energization of one displacing unit (forone direction of displacement) and of one advancing unit can result inthe movement of but a single actuating link into the cam path, so thateach pair of energizations gives a unique result.

Figs. 6 and 7 show an illustrative structure embodying the fingers 96and the motive means 90 and 114 as mounted within theimpeller drum 30.Seven advancing units 90 are shown, each serving four fingers 96; andsince there is provision for deflecting each finger in either directionto serve either of two actuating links 20, there are four double-actingdisplacement units 114.

The arcuate comb member 38, providing slots between its teeth 39 whichreceive the ends of the actuating links 20, is located as in Figs. l-4in the lower half-circle of the impeller drum 30.so that as the drumrotates the cams on its flange 31 pass in close proximity to the outeredges of the actuating links. Motion of the end of any link 20 radiallyoutward brings its cam-follower portion 57 into the pathtof the cams.

The fingers 96 for selectively moving the actuating links 20 in thatmanner are arranged radially in seven groups of four each in the lowerhalf of the circle. Each group of four has motive means such as theelectromagnetic actuator 90 which is secured by bosses 84 to .a backplate 80 carried by the machine frame and having a bored central bosswherein is journalled the forward end of the spindle 32 of the drum 30.Each of the electromagnetic actuators 90 comprises a U-shaped magneticstructure 86. (Fig. 7) having a central core piece 88 about which iswound an electric solenoid B9. The magnetic circuit is completed throughan armature 92 which extends transversely between the ends of the armsof the structure 86. When the solenoid .89 is energized, the armature 92is in contact with the end of thecore piece88gand the ends of the armsof the magnetic structure 86 as is shown in Fig. 7. When the solenoid 89is deenergized, the armature 92 is biased by a spring 94 so that itpivots about the end of the left hand magnetic structure leg to a normalposition wherein there is an air gap between the armature and the corepiece 88. The free end of the armature 92 carries the fingers 96 whichare secured to it in any suitable way, being disposed at a substantiallyright angle to the end of the armature so as to extend radially outwardof the circle at the front, into close proximity to the inner edges ofthe actuating arms 20.

The fingers .96 are of a resilient material such as a suitable springmetal. Normally the fingers project outwardin a direction in line withthe spaces between the actuator links and in line with the teeth 39 ofthe comb member 38. Thus, energization of the solenoid 89 of one ofthese actuators 90 causes its armature 92 to be drawn against the end ofthe core piece 88, overcoming the retracting force of spring 94, withthe result of advancing the attached four fingers 96 into the spacesbetween adjacent actuator links 20. Each finger 96 serves two links 20alternatively, the finger being capable of pivoting in either directioninto register with either of the links defining the space with which thefinger normally registers. If, for example, the unit is to be used withamanual keyboard having keys similar to those shown in Fig. 1, eachactuator 90 is energized through circuit control means such as a switch(not shown) which is closed by the operation of any one of eight.associated keys 40, so that if anyof the eight keys is struck the groupof four fingers 96 operated by that actuator is advanced axially.Further, the relation of these eight keys to the displacing units 114 issuch that only one ofthe fourfingers of the particular group is '8displaced laterally, .and in a particular direction, when any of theeight keys is struck; and the advanceof fingers results .in the movementof only one actuating link 20 intothe cam path.

The four double-acting electromagnetic displacingunits 114 arepositionedin the upper portion of the drum circle and serve to impart asmallangular motion in either direction to the fingers 96. This isaccomplished by passing each of the fingers 96 through an aperture in aninwardly turned .tab 100 which extends at right angles from the edge ofone of four sector shaped frames 102 and 104 which are journalled torotateon the fixed central boss 106 extending from the back plate 80,The sector frames 102 and 104 lie in substantially :vertical planes, twoin front of and two behind the bank, of fingers 96. Each sector frame102 and 104 consists of a thin metal sheet formed as a diametral web 93mounted on the boss 10,6, and an arcuate web-connected at its ends tothe ends of the diametral web. Thearcuate webs of the two outside frames102cm either of the bank of fingers have a greater radial dimension thanthe webs of the two inner frames 104 so that the webs do not overlie oneanother. Each arcuate web carries seven inturnedspaccd tabs 100 througheach of which there extends one of the fingers 96 advanCQd axially byeach of the actuators or, using the same terminology as above, one framehas holes so located as to receive the Aa fingers of each ofthe sevengroups; anotherreceives the Bb fingers, etc. Slight rotation of theframe under action of the actuator 114 associated with it displaces allof the sevenconnected fingers passing through the tabs of that frame bydeflecting the fingers laterally.

The sector frames 102 and 104 are rotated by means of a second setofelectromagnetic actuators 114, .four

of which are mounted upon a plate 110 spaced from the top half of theback plate 80. Each of the actuators 114 has two separate .magneticstructures 112 with axially aligned central core pieces upon each ofwhich is wound a respective solenoid 108.. Interposed between the endsof the core pieces is a common armature 116 one end of which is pivotedat 118 so that armature is movable in either direction by thecnergization of the-corresponding solenoid 108. The otherendof thearmature 116.carries apin 124 which is located between twolcat springmembers 120 whose ends are fixed as at that the armature is normallyheld in a centralposition between the pole pieces. The pin 124 alsoextends through a slot in an arm extending from a corresponding frame102 or 104, so that as the armature 116 is moved in either direction bythe energization of a corresponding solenoid 108, the interconnectedsector frame is rotated in either a clockwiseor counterclockwisedirection about the hub 106. The tabs 100 on-the inter.- connectedsector frame move one finger 96 associated with each group advanced bythe first set of electromagnets 90 so that such fingers are deflectedeither to the leftor right to position the ends thereof above-theadjacent links 20.

It will be evident from the above that each combination of twoelectromagnetic actuators selected from both the first and second setswill result in the lateral deflection of seven fingers 96 (one-from eachgroup) and the axial advance of four fingerstof one group) so that ofthe seven fingers brought into register with their respective links 20only one is advanced to contact the link, i.;e., for every combinationof actuators one. (and only one) link is motivated. While it is probablybest from a theoretical standpoint to complete the lateraldeflection of.a finger 96 before the finger is advanced, I have found as a practicalmatter that because the distance which a finger is advanced ismaterially greater than the amount of deflection required, no :timedelay other thanthat inherent-is required and it is possible to.obtainsuccessful operation when both electromagnetic actuators of acombination are energized simultaneously. If the electromagnetic actionis to be used in a typewriter which is manually operated a keyboardhaving keys 40 mounted near the end of a pivoted arm 41, similar to thatillustrated in Fig. 1, may be used. The movement of each key arm 41 asthe corresponding key 40 is struck may be used to close the contacts oftwo normally open switches (not shown) which complete circuitsenergizing the electromagnet solenoids 89 and 108 of the actuatorcombination that pivots the link 20 connected with the type barcorresponding to the struck key.

It will be evident that a material saving in the number of switchesrequired can be made by providing only one switch for energizing each ofthe electromagnet solenoids 89 and 108 and having each switch closed byoperation of any of several keys. As there are 56 links and only eightdeflecting actuator solenoids 108, each solenoid must be energized bythe operation of any of seven keys. Similarly, as there are sevenadvancing actuators 90 each must service eight links so that eachassociated switch must be closed by the operation of any one of eightkeys. The closing of the switches by any of several keys is readilyaccomplished by a simple mechanical linkage interconnecting each switchoperating member and the arms 41 of its associated keys, the onlyprecaution required being that the operation of each key close the twoswitches which will energize a unique combination of two solenoids oneof which is selected from the first set of actuators 90 and the otherfrom the second set of actuators 114.

As the only requirement for operating any particular type bar 10 is theenergization of one combination out of 56 possible combinations ofsolenoids, it will be evident that the present invention is not limitedto use with a manual keyboard but is also applicable to robot and cardoperated typewriters or other machines wherein an output of printedcharacters in required, the only requirement being that the machineincorporate an electrical circuit which will selectively emit anycombination of two electrical pulses from a total of 56 pulses.

I claim:

1. A typewriting machine comprising means for moving the copy along apredetermined path, a plurality of type bars pivotally mounted in anarcuate group so that each can selectively be brought into contact withthe copy at the same point along the copy path, a plurality of baractuating links one end of each of which is operatively interconnectedwith a corresponding type bar, a continuously rotating hollow drum openat one end and having a plurality of raised cammed surfaces upon itsinner surface Whose locus is disposed adjacent the other ends of thelinks, the links extending into the drum through the open end thereofwith said other ends of the links normally spaced from the path of saidcammed surfaces, and motivating means for selectively bringing therespective links into operative engagement with a random cammed surfacewhereby a free flight movement is imparted to the selected link andconnected type bar to bring the bar into forcible contact with the copy.

2. A typewriting machine comprising means for moving the copy along apredetermined path, a plurality of type bars pivotally mounted in anarcuate group so that each can selectively be brought into contact withthe copy at the same point along the copy path, a plurality of baractuating links one end of each of which is pivotally connected to acorresponding type bar, a continuously rotating hollow drum open at oneend and having a plurality of cammed surfaces upon its inner surfacewhose locus is disposed adjacent the other ends of the links, the linksextending into the drum through the open en thereof with said other endsof the links normally spaced from the path of said cammed surfaces, andmotivating means for selectively rotating the links about their pivotalconnections to bring the respective links into operative engagement witha random cammed surface whereby a free flight movement is imparted tothe selected link "10 and connected type bar to bring the bar intoforcible contact with the copy.

3. A typewriting machine comprising means for moving the copy along apredetermined path, a plurality of type bars pivotally mounted in anarcuate bank so that each can selectively be brought into contact withthe copy at the same point along the copy path, a plurality of baractuating links, one end of each of which is pivotally connected to acorresponding type bar upon the opposite side of the bar pivot pointfrom the copy contacting portion of the bar, a continuously rotatinghollow drum open at one end andhaving a plurality of cammed surfacesupon its inner surface whose locus is disposed adjacent the other endsof the links, the cammed surfaces being shaped to move substantiallylengthwise a link brought into contact therewith, the links extendinginto the drum through the open end thereof with said other ends of thelinks normally spaced from the path of said cammed surfaces, andmotivating means for selectively rotating the links about their pivotalconnections to bring the respective links into operative engagement witha random cammed surface whereby a free flight movement is imparted tothe selected link and connected type bar to bring the bar into forciblecontact with the copy.

4. A typewriting machine comprising means for moving the copy along apredetermined path, a plurality of type bars pivotally mounted in anarcuate group so that each can selectively be brought into contact withthe copy at the same point along the copy path, a plurality of baractuating links one end of each of which is pivotally connected to acorresponding type bar upon the opposite side of the bar pivot pointfrom the copy contacting portion of the bar, a continuously rotatinghollow drum open at one end and having a plurality of cammed surfacesupon its inner surface whose locus is disposed adjacent the other endsof the links, the cammed surfaces being shaped to move substantiallylengthwise a link brought into contact therewith, the links extendinginto the drum through the open end thereof with said other ends of thelinks normally spaced from the path of said cammed surfaces, andmotivating means for selectively rotating the links about their pivotalconnections to bring the respective links into operative engagement witha random cammed surface whereby a free flight movement is imparted tothe selected link and connected type bar to bring the bar into forciblecontact with the copy.

5. A typewriting machine according to claim 4 wherein the motivatingmeans includes a plurality of electromagnetically operated actuators forpivotally moving the links selectively to bring the ends thereof intoengagement with the cammed surface. a

6. A typewriting machine comprising means for moving the copy along apredetermined path, a plurality of, type bars pivotally mounted in anarcuate group so that each can selectively be brought into contact withthe copy at the same point along the copy path, a plurality of baractuating links one end of each of which is pivotally connected to acorresponding type bar upon the opposite side of the bar pivot pointfrom the copy contacting portion of the bar, a continuously rotatingdrum having a plurality of cammed surfaces whose locus is disposedadjacent the other ends of the links, the cammed surfaces being shapedto move substantially lengthwise a link brought into contact therewith,motivating means for selectively rotating the links about their pivotalconnections to bring the respective links into operative engagement witha random cammed surface whereby a free flight movement is imparted tothe selected link and connected type bar to bring the bar into forciblecontact with the copy, a plurality of fingers for selectively rotatingthe respective links about their pivots to bring the ends thereof intoengagement with the cammed surfaces, the fingers between arranged in aplurality of groups, a set of electromagnetic actuators each of whichsimultaneously advances axially the fingers of a respective group sothat the end of each of the fingers passes between two adjacentalinks,and a second set of electromagnetic actuat'ors each of whichsimultaneously deflects laterally one finger from each group to bringthe ends of the deflected fingers into register with the adjacent linksto one side thereof whereby the energization of any combination of twoelectromagnetic actuators selected from the first and second setswillrotate only one of the links corresponding. to such combination.

1 7.. A-typewriting machine according to claim 6 wherein=the number ofactuators in the second set corresponds in: number to the number offingers in each group, each actuator in the second. set being arrangedto deflect the fingers associated therewith in either of two opposeddirections so as selectively to bring the fingers in register with. thelinks to either side of the normal undeflected positions of the fingers.

8. .A typewriting machine according to claim 7 wherein? the fingersextend substantially radially outwardly from the axis of rotation of thedrum and each of the actuators of the second set is provided with amember which is rotatable about the drum axis in either direction by theactuator, each member interconnecting with one finger from each group sothat the interconnected fingers are deflectable laterally in eitherdirection.

9; A typewriting machine according to claim 8 wherein'each'electromagnetic actuator of the second set ineludes two independentlyenergized solenoids having a common armature suspended therebetween, thearmature being connected with a respective one of the members whichrotate about the drum axis so that energization of. either of thesolenoids causes the member to be rotated in a corresponding direction.

10; A typewriting machine comprising a movable platen, a plurality oftype bars pivotally mounted in an arcuate group so that each canselectively be brought into contact with the platen, a plurality of baractuating links one end of each of which is pivotally connected to acorresponding type bar upon the opposite side of the bar pivot pointfrom the platen contacting portion of the' bar, a continuously rotatingdrum having a plurality of cammed surfaces whose locus is disposedadjacent the other ends of the links, the cammcd surfaces being shapedto move substantially lengthwise a link brought into contact therewith,motivating means for selectively rotating the links about their pivotalconnections to bring the respective links into operative engagement witha random cammed surface whereby a free flight movement is im-' parted tothe selected linkand connected type bar to bring the bar into forciblecontact with the platen, and means for controlling the force with whichthe type bars strike the platen including a plurality of compressionsprings, and a tension rod extending between one end of. each respectivespring and the same side of a correlated type bar as that to which thelink is pivotally connected.

11. A typewriting machine according to claim 10 whereinis furtherprovided means for adjusting the bias imposed by the impression controlsprings so as to vary the striking force of the type bars.

12. A typewriting machine according to claim 10 wherein is'furtherprovided means for independently adjusting the force exerted by eachspring.

13; A typewriting machine according to claim 12 wherein the means forindependently adjusting the force exerted by each spring includes meansfor varying the relative point of connection of the end of each springto the corresponding rod thereby to change the initial spring biasingforce.

14. .A typewriting machine according to claim 10 wherein is furtherprovided means for simultaneously changing the biasing forces exerted bythe springs thereby to vary the impression of the type bars upon theplaten.

15. A typewriting machine according to claim 14 wherein the means forsimultaneously changing the spring forces includes a common member forsimultaneously moving the opposite ends of the springs thereby to changethe initial spring. biasing force of all of the springs.

16. A typewriting machine comprising a movable platen; a plurality oftype bars pivotally mounted in an arcuate group so that each canselectively be brought into contact with the platen, a plurality of baractuating links one end of each of which is pivotally connected to acorresponding type bar upon the opposite side of the bar pivot pointfrom the platen contacting portion of the bar, a continuously rotatinghollow drum open at one end and having a plurality of cammed surfacesupon its inner surface whose locus is disposed adjacent the other endsof the links, the cammed surfaces beingshaped to move substantiallylengthwise a link brought into contact therewith, the links extendinginto the drum through the open end thereof with said other ends of thelinks normally spaced from the path of said cammed surfaces, motivatingmeans including a plurality of pivotally mounted levers each of which isjoined with a respective link by means of a slidable connection so asnot to interfere with the lengthwise movement of the link by the carnmedsurfaces, a plurality of keys and means interconnecting the levers withthe respective keys so that depressing a selected key rotates thecorrelated lever andlink about their associated pivots to bring the endof the link into operative engagement with a random cammed surfacewhereby a free flight movement is imparted to the selected link andconnected type bar to bring the bar into forcible contact with theplaten.

17. A typewriting machine according to claim 16 wherein the meansinterconnecting the levers with the correlated keys includes a pluralityof mechanical linkages.

18-. A'typewriting machine according to claim 17 wherein each of themechanical linkages includes a ratchet operated by the depressing of thecorrelated key and a flexible cable one end of which is connected to theassociated lever, the other end of the cable being wound on the ratchetby' the operation thereof thereby to rotate the lever and initiate themovement of the associated type bar.

References Cited in the file of this patent UNITED STATES PATENTS869,526 Secor Oct. 29, 1907 1,199,824 Schluns Oct. 3, 1916 1,202,878Morley Oct. 31, 1916 1,395,600 Satterstrom Nov. 1, 1921 1,737,439Stickney Nov. 26, 1929

